The testing of electronic components or devices during manufacturing involves use of a test fixture to accurately position the device under test so that electrical contacts are properly engaged to perform the test. Inaccurate placement or lack of appropriate electrical contact could result in a false rejection of the device under test and significant waste.
For example, power contacts and control system contacts on circuit board devices are engaged with matching contacts on a test fixture by manually or mechanically placing the circuit board device on the test fixture. Guide pins or other physical barriers are located on the test bed to accurately guide and locate the device to be tested into the correct testing position.
In a circuit board device, the electrical contacts may be soldered, or engaged with tight fitting connectors, and the circuit boards are usually snap-locked, fastened or clamped securely in a housing to avoid malfunctions or short circuits in use.
However, in a test fixture, such secure means of making electrical contacts are inefficient and would interfere with the speed of testing required during manufacture. Test fixtures therefore include temporary means of making electrical contact which minimize the risk damage to the device under test and which aim to involve minimal time in positioning and withdrawing the devices under test to increase the speed of testing.
Since many electronic devices are very light weight and flexible, merely placing the devices in a test fixture is insufficient to ensure that proper electrical contact is made. Commonly the device is physically clamped to exert pressure on the matching electric contacts and ensure that a reliable connection is made for conducting the testing procedure.
Pneumatic, hydraulic or mechanical clamping systems, including robotic systems are commonly used for this clamping function. However, all such systems require physical space in the manufacturing facility, require maintenance due to inevitable wear and tear of moving parts, and require periodic adjustments to maintain accuracy, consume power, impose operating and capital costs, and often create significant noise or safety hazards. In many cases, the test fixture and associated clamping system must be housed within a protective housing such as a radio frequency housing, a noise suppression housing, a dust proof housing, a temperature controlled housing or other protected environments. The use of mechanical, pneumatic or hydraulic clamping systems significantly increases the necessary space volume of any protective enclosure consuming manufacturing space and imposing various costs on the manufacturing process.
Further details of the test fixture and its advantages will be apparent from the detailed description included below.